`sl config --local section.name` behaves differently from `sl config section.name` (and in an unexpected way)

[Diego Elio Pettenò]

$ sl config hooks.pre-commit
.sl/pre-commit/pre-commit-hook.sh
$ sl config --local hooks.pre-commit
abort: missing config value for 'hooks.pre-commit'

It seems like --local implies editing, but that is not well documented in the help message, and is surprising, particularly when compared to the git config equivalent.

[Muir Manders]

I'll try to improve the error message.

Sapling doesn't support reading config only from a particular source. If you use "--debug", it will show all the locations the value is configured (and which takes precedence).